Abstract The proposed grant is an approved ancillary study to the Dietary Approaches to Stop Hypertension for Diabetes Trial (DASH4D), a randomized clinical trial being conducted at Johns Hopkins University. The overarching goal of this ancillary study is to evaluate how a controlled diet (as part of this feeding study) modifies glucose control and glycemic variability in black and white adults with type 2 diabetes. The objective of the DASH4D trial is to determine the effects, alone and combined, of (a) the DASH4D diet (a DASH-style diet modified for people with type 2 diabetes) vs. comparison diet typical of what many Americans eat and (b) lower sodium intake vs. higher sodium intake on blood pressure among people with type 2 diabetes and elevated blood pressure. The core design is a single-site, 4-period, crossover feeding study with 5-week periods. Participants will be fed each of four isocaloric diets in random order. The proposed ancillary study will add continuous glucose monitoring and laboratory testing of complementary biomarkers in all participants in the DASH4D trial during two weeks of each of the four feeding periods. Our overarching goal is to answer the question: Does a diet rich in fruits and vegetables improve glucose control and reduce glycemic variability in adults with type 2 diabetes?